Several user-propelled vehicles have been introduced which allow the rider of the particular vehicle to propel the vehicle using the rider's limbs. These devices are preferred in certain applications over electrically-powered wheelchairs because user-propelled wheelchairs can, among other things, exercise the user's muscles while providing a means for the user to move about.
In one application for such vehicles, several wheelchairs have been introduced that include provisions for permitting the user of the wheelchair to propel the wheelchair. An example of one user-propelled wheelchair is shown in U.S. Pat. No. 4,506,900 to Korosue. The Korosue patent discloses a wheelchair having a lever that can be urged against by the user to impart torque, through a linkage system, to the wheels of the chair. Another user-propelled wheelchair is discussed in U.S. Pat. No. 4,865,344 to Romero, Sr. et al. As disclosed in the Romero, Sr. et al. patent, the wheelchair can be propelled by the user by urging against a portion of a push rod that is mounted on the frame of the Romero, Sr. et al. device. By urging on the push rod, the user generates a torque which can be imparted to the wheels of the device through a linkage system.
Unfortunately, the devices mentioned above can be difficult for some users to operate. More particularly, it may be difficult for a user whose fingers are debilitated to operate the propulsion levers of the devices mentioned above. Furthermore, users with limited use of their hands or fingers can find it difficult to steer such devices. Additionally, the devices mentioned above do not provide for augmenting the propulsive force imparted by appropriate movement of the user's upper body with propulsive force that can be supplied by the user's legs and feet. Thus, the devices mentioned above do not efficiently use all of the user's muscle power. Looked at in a different light, the devices above stimulate or exercise only a few body muscles of a user. This is unfortunate, because certain wheelchair users can benefit from the exercise and stimulation of partially debilitated leg muscles.
Furthermore, the devices mentioned above do not provide for easily adjusting the configuration of the devices to suit the physique of the user. Also, the devices mentioned above cannot be folded for easy storage of the wheelchair. The present invention recognizes that a user-propelled foldable wheelchair can be provided which can be easily steered by a person with a limited range of arm or finger motion, for example, a person with only one hand and no fingers, and which can exercise the person's leg or legs.
Accordingly, it is an object of the present invention to provide a user-propelled wheelchair which can be easily steered by a person with a limited range of arm or finger motion. It is another object of the present invention to provide a user-propelled wheelchair which can exercise the user's legs. A further object of the present invention is to provide a user-propelled wheelchair which is foldable and which is configurable to suit the physique of the particular user. Yet another object of the present invention is to provide a user-propelled wheelchair which is easy to use and cost-effective to manufacture.
In another application of user-propelled vehicles, several skateboards have been introduced which can be propelled by the user of the skateboard without requiring the user's foot to touch the ground. One example of such a device is the skateboard disclosed in U.S. Pat. No. 3,399,906 to Portnoff. The Portnoff patent discusses an occupant-propelled skateboard in which the motive force is supplied by the occupant through a pedal that is connected to a toothed arm. In accordance with the Portnoff invention, the toothed arm is ratchetably engaged with a gear, and the gear is attached to a rear axle of the skateboard. When the pedal is depressed by the occupant, the resulting torque is transferred through the arm and gear to the rear axle to propel the skateboard.
While skateboards such as the Portnoff invention do not require the user to touch the ground in order to propel the skateboard, it is unfortunately the case that such skateboards characteristically introduce mechanical complications relating to the steering of the skateboard. More particularly, most skateboards are steered by the operator of the skateboard by the operator appropriately shifting his weight on the board. When the operator shifts his weight to change the direction of the skateboard, the surface of the skateboard on which the operator stands tilts toward the intended new direction of motion.
It will be appreciated that while the skateboard's surface tilts, the wheels of the skateboard are intended to remain rollably engaged with the ground. Thus, relative tilting motion between the surface of the skateboard and the skateboard's wheels occurs whenever the direction of the skateboard is changed. Unfortunately, this tilting motion of the skateboard's surface relative to the wheels of the board can interfere with the smooth rotation of, for example, a drive gear such as the Portnoff drive gear, and thereby impede the operation of the skateboard.
Furthermore, the Portnoff skateboard cannot be slowed without abruptly stopping the skateboard. Specifically, the Portnoff skateboard, and most conventional skateboards, do not provide a direct means for retarding rotation of the wheels of the board. Instead, to stop the board, the user ordinarily must stop the board by jumping off or by causing a portion of the skateboard's surface to contact the ground.
The present invention recognizes that a user-propelled skateboard can be provided which permits tilting motion of the skateboard's surface relative to the wheels of the skateboard without unduly interfering with the propulsion components of the board. Also, the present invention recognizes that a skateboard can be provided in which the rotation of the wheels of the skateboard can be slowed by the user.
Accordingly, it is an object of the present invention to provide a user-propelled skateboard which permits tilting motion of the skateboard's surface relative to the wheels of the skateboard without unduly interfering with the propulsion components of the board. It is another object of the present invention to provide a user-propelled skateboard in which the rotation of the wheels of the skateboard can be slowed by the user without the user having to contact the ground or other object not part of the skateboard. Another object of this invention is to provide a user-propelled skateboard that can with practicality pull a hauling cart behind it. Yet another object of this invention is to provide a user-propelled skateboard in which the front can be elevated in such a way that the skateboard, balanced on one wheel somewhat like a unicycle, can be propelled by the hands and/or one foot, and in which a new variety of single wheel type steering can then be used. Still another object of the present invention is to provide a user-propelled skateboard which is easy and fun to use and cost-effective to manufacture.